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Structural health monitoring based on vibration measurements is a process that implements the instrumentation of sensors and methodologies to provide information regarding the condition of a structure, which allows the evaluation of the safety and integrity of structural systems. Because of this, in the past decades, several algorithms have been developed; among them, the wavelet transform is considered an efficient method for the elimination of the error contained in the acceleration recorded by the sensors. However, due to the complex nature of earthquakes and the particularity of the structural systems, the parameters used by the wavelet transform for error elimination in the seismic response are frequently variable. This paper proposes a method to get the seismic response of a base-isolated building subjected to ground-strong motions through numerical simulations of a mathematical model of the structure, using synthetic records based on historical seismic events occurring in Peru. In this way, the research found that the optimal intrinsic parameters of the building correspond to an approximate frequency interval of 0.20 to 6.25 Hz. Finally, the results show that this method is valid and can be reliably applied in structural health monitoring systems.

Significant attention has been recently paid to the determination of floor acceleration demands used for the design of acceleration-sensitive non-structural components in buildings. This study makes a contribution through the use of experimental shake table data from one 6-storey and two 3-storey reinforced concrete buildings tested at the E-Defense testing facility. All buildings were exposed to multiple excitations, and floor acceleration demands were studied through peak floor accelerations and floor response (acceleration) spectra. The obtained ratios of peak floor to peak ground accelerations confirmed findings from previous studies. The ratio distributions along the height provided in Eurocode 8, ASCE 7-16 and NZS 1170.5 were found to be conservative. Besides the known properties of floor response spectra, the results for two of the buildings revealed that in some cases, spectra can have two prominent peaks corresponding to the fundamental mode period of different damage states or degree of nonlinearity during a single shaking event. A prerequisite for this occurrence, which in this paper is termed the “Elongated Fundamental Mode Effect”, is that due to the characteristics of the input motion, a significant part of the energy is involved both before and after the change of structural response nature, from (mostly) linear elastic to nonlinear. Among others, such change is perceptible through an extension of the fundamental period. The Elongated Fundamental Mode Effect was investigated by using scalograms generated through the Continuous Wavelet Transform, which was found to be an efficient tool for the visualization of energy localization in the time–frequency domain.

Earthquakes and tsunami disasters happen suddenly, devastating cities in just a few minutes. For decision makers to manage such disasters, they need current information on the status of their cities, but all information is collected separately and on paper now. All disaster-related information should be integrated to support decision making. To develop such an integrated system, Peru and Japan launched a new SATREPS project, “Development of Integrated Expert System for Estimation and Observation of Damage Level of Infrastructure in Lima Metropolitan Area,” in 2021. The project consists of four groups. Group 1 is related to earthquake and tsunami hazards, estimating the level of shaking and predicting the damage due to tsunami. Group 2 is related to damage detection/estimation, using sensing devices to estimate the level of damage to buildings and other infrastructure. Group 3 is related to understanding the damage over a wide area through satellite images, and also to the integration of all information from Groups 1 to 3. Group 4 is related to developing the capacity to utilize the integrated expert system. This special issue has been organized to present the progress accomplished in the first two years and to share the project’s achievements. It covers the fields of earthquake hazards, building and infrastructure damage estimation, damage estimation with satellite imagery, and human loss estimation.

Shake-table tests of a 3-story reinforced concrete building with cladding casted to be monolithic with frame elements, with seismic slits or cut reinforcing bars present in some cladding elements t...

Pushover analysis is widely used in modern practical structural design to evaluate collapse modes and member forces at the safety limit state. All members, including shear walls, need to be modeled properly to assure the accuracy of pushover analysis. As such, functions to predict initial stiffness, crack strength, yield or ultimate strength, stiffness degrading ratio to the yielding point, ultimate deformation, and ultimate shear strength must be acceptably accurate. While several theoretical, semi-theoretical, and empirical functions have been proposed and are commonly used in practice, the accuracies of these functions have not been verified comprehensively. The Ministry of Land, Infrastructure, Transportation and Tourism and the Building Research Institute launched a project in Japan from 2012 to 2015 to develop a comprehensive database of experimental data from 507 reinforced concrete wall experiments conducted between 1975 to 2013 to confirm the accuracy of the functions. In this paper, the comparisons between values predicted using the functions against experimental results from the database are presented. It was found that (i) the predicted initial stiffness tends to be higher than that from experimental tests, (ii) the predicted ultimate flexural and shear strengths were generally smaller than those from experimental tests, and its accuracy appears to be dependent on the presence of boundary columns and the existence of openings, and (iii) the predicted deformation corresponding to yield and at ultimate shear strength tends to be smaller than those from experimental tests.

Capacity curve estimated from seismic floor accelerations can provide an informative description of the structural behavior soon after an earthquake. Detailed information on instrumented buildings ...

In this paper, the plastic design with mechanism control (PDMC) for steel moment resisting frames (MRFs) is presented. The PDMC method in rigid plastic analysis, by considering the second-order effects, is guaranteed the achievement of global mechanism and prevented undesired mechanisms such as the soft story, which leads to decrease the ductility and energy dissipation capacity of the structures. The concept of PDMC is based on the plastic rotation of columns in developing a mechanism in which for a specified target displacement, the global mechanism has a minimum plastic rotation among all other undesired collapse mechanisms. In the presented method, the design conditions for story mechanisms are derived by using an energy equilibrium equation. For demonstrating the accuracy of the proposed design procedures, both pushover and nonlinear incremental dynamic analyses (IDAs) are applied to evaluate the structural performance. The results show that the designed structures comprise high seismic performance and the design objective that was to obtain a global mechanism is achieved.

In this paper, optimum plastic design using mechanism control (PDMC) for steel moment resisting frames (MRFs) is presented. The PDMC method in the solid plastic analysis, by considering the second-order effects, achieve the global mechanism and prevent undesired mechanisms, which leads to decrease the ductility and energy dissipation capacity of structures, is guaranteed. The concept of the PDMC is based on the plastic rotation of columns in developing a mechanism in which for a specified target displacement, the global mechanism has a minimum plastic rotation of columns among all other undesired collapse mechanisms. In terms of involving optimization to the PDMC procedure, two methods are considered: 1) based on the sum of the reduced plastic moment of columns in each story, 2) based on the plastic moment of all members. For both methods, minimum structural weight is obtained by defining a linear programming problem. To show the accuracy of the design procedure, three frames consisting of four, eight, and twelve-story MRFs are designed by two methods, then they evaluated under the pushover and the IDA analyses. The results indicate that the designed frames by the second method have less weight compared with those designed using the first method. However, frames designed by both mentioned methods had high seismic performance and the design goal that is attaining to the global mechanism is achieved.

This paper focuses on the development and verification of a unified calculation method for estimating the yield of reinforced concrete (RC) beams, columns, and walls deformation considering flexural deformations, shear deformations, and bar slip deformations. Each component of yield deformation is considered independently, and the estimated yield deformation is the sum of these three parts. To verify the accuracy of this method, yield deformation results from a database of experimental results from tests performed in Japan on RC components was compared against those predicted by the proposed methods. The results show that the proposed method provides a reasonable prediction of the yield deformation and show that the proposed method has a better estimate of yield deformation than other previous methods. Sensitivity analysis on the influence of the rigidity reduction rate due to the shear effect, and the anchorage length in the bar slippage calculation, was performed. It was found that the rigidity reduction rate factor could influence the accuracy for walls. The influence of other material and member characteristics are also discussed herein.

This paper presents a new method that involves the use of a double integral with a wavelet transform for computing the capacity curve of a system with multiple degrees of freedom. The displacement response of a building is derived from measurements of its acceleration, thus facilitating the assessment of the damage to the building as soon as possible after an earthquake. The validity of the method is assessed against existing shaking‐table results for a reinforced concrete structure.

Recently, earthquake damage to non-structural walls has become one of the important issues in Japan. Some buildings were demolished after the 2011 Tohoku Earthquake due to damage of non-structural walls without any significant damage in structural members. After that, several projects were launched to develop a new method to take into account the effect of non-structural walls (hanging, standing, and wing walls). In this paper, experimental test results for beam-column joints with non-structural walls are presented. The objectives of the tests were to investigate the equivalent length and hinge location of beams with hanging and standing walls. The results showed that the yield hinge located at the surface of the wing walls and beam-column joint should be modelled as rigid to estimate the deformation of the beams, regardless of the thickness and height of the wall. A tri-linear modelling method for beams with hanging and standing walls was also proposed, and its applicability was confirmed with the test results.

The author has developed a new method for evaluating the seismic performance of existing structures from measured accelerations based on the capacity spectrum method. This involves comparing the performance curve, which is the equivalent nonlinear behavior of a simplified single-degree-of-freedom system, and the demand curve, which is the relationship between the response acceleration and displacement spectra. Two telecommunication towers in Japan were instrumented in 2016, and their responses during several earthquakes have been recorded. This paper discusses the evaluation of damage during the two earthquakes. Moreover, parameters such as the predominant period and the required performance are discussed. The proposed system evaluated both towers as being “elastic.” The damping ratios of the towers are very low, which caused the oscillations to continue for more than 5 min after the mainshock of each earthquake because of long-period components of the seismic motion

Safety evaluations of existing buildings considering aftershocks are essential for occupants after an earthquake. To this end, a capacity-curve-based method is proposed using the seismic response data from the mainshock, which is quantitatively suitable for a damage prediction after an aftershock. The predicted maximum response during the mainshock–aftershock sequence is the intersection of the demand curve and the capacity curve of the structure, after which the damage class can be judged. The feasibility of the proposed method is verified using a numerical method, and comparisons are made between the results of proposed method and the code-specified method in Japan. It is shown that the proposed method can provide a good estimate for damage evaluation for aftershocks.

The author has developed a new method for evaluating the seismic performance of existing structures from measured accelerations based on the capacity spectrum method. This involves comparing the performance curve, which is the equivalent nonlinear behavior of a simplified single-degree-of-freedom system, and the demand curve, which is the relationship between the response acceleration and displacement spectra. Two telecommunication towers in Japan were instrumented in 2016, and their responses during several earthquakes have been recorded. This paper discusses the evaluation of damage during two earthquakes. Moreover, parameters such as the predominant period and the required performance are discussed. The proposed system evaluated both towers as being “elastic”. The damping ratios of the towers are very low, which caused the oscillations to continue for more than 5 min after the mainshock of each earthquake because of long-period components of the seismic motion.

Efficient and quantitative damage inspection is essential for safety assessment of existing structures after an earthquake event. This paper proposes an approach for assessing the damage condition of reinforced concrete (RC) buildings using seismic response data in terms of the relationship between the mass-normalized force and deformation of an equivalent single-degree-of-freedom system, which enables a quick diagnosis of the overall structural condition in a quantitative manner. An experimental investigation is presented, and comparison between the proposed and code-specified visual-inspection methods is made based on the result of a full scale six-story RC wall-frame building shaking table test. We show that the damage-evaluation results using the proposed method agree fairly well with those of the visual inspection during the tests.

Design codes prescribe equations for the ultimate state design of RC walls with flange walls as boundary elements. These codes consider part of the length of the flange wall as a width that will effectively resist lateral loads. However, wall damage and the accuracy of the effective width used in the calculations have not been sufficiently discussed. Therefore, a loading test is carried out at Yokohama National University on two 1/3 scale specimens in order to evaluate the strength, damage, energy dissipation, and behavior of RC structural walls in flexure. One specimen without flange walls and one with flange walls are tested. The strength and response of each specimen are described, and the prediction accuracy of the design flexural strengths given by design codes ACI, Eurocode, and AIJ are examined. Experimental strain data are used to describe the behavior of the flange wall in order to understand the mechanism and to confirm the accuracy of the effective width prescribed by the design codes in terms of tension and compression. The result of the experimental study reveals that design prescriptions given by ACI, Eurocode, and AIJ guidelines can conservatively estimate the flexural strength for RC walls without flanges, but they underestimate the flexural strength for flanged walls. This underestimation is due to a lack of knowledge of the mechanism that develops at the flange. It is not possible to determine a specific value for flexural effective width. However, according to the results of calculations, a portion larger than the width proposed by the aforementioned design codes serves to resist the stresses imposed by lateral loads. Therefore, it is confirmed that the flange width is underestimated by the design codes, and it increases with the imposed drift level. The stress distribution at the flange in the out-of-plane direction is found not to be uniform, a fact that is at odds with design assumptions.

The neutron diffraction technique was applied to measure strain distributions in a rebar in a reinforced concrete. At first, absorption coefficients of several kinds of concrete with different compounding ratios of water, cement, and aggregate were measured, and it was confirmed that the absorption coefficient of concrete was affected by the amounts of water and aggregate. In addition, it was also clarified by measuring strain change of the rebar under tensile loading that accuracy of the strain measurement in the rebar in the reinforced concrete was not affected by the neutron absorption by the concrete. Second, the size of the anchorage zone was evaluated by measuring strain distributions in the rebar under pull-out loading. The length of the anchorage zone measured by neutron diffraction was shorter than that measured by strain gauges. Moreover, detailed strain distributions in the rebar around cracks in the concrete were measured under tensile loading, and it was confirmed that the bond condition between rebar and concrete around cracks could be evaluated using the neutron diffraction technique.